//rem 转化
(function (doc, win) {
  var docEl = doc.documentElement,
    resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
    recalc = function () {
      var clientWidth = docEl.clientWidth;
      if (!clientWidth) return;
      docEl.style.fontSize = 200 * (clientWidth / 750) + 'px';
    };
  if (!doc.addEventListener) return;
  win.addEventListener(resizeEvt, recalc, false);
  doc.addEventListener('DOMContentLoaded', recalc, false);
})(document, window);
//ios 禁止页面缩放
window.onload = function() {
  document.addEventListener('touchstart', function(event) {
    if (event.touches.length > 1) {
      event.preventDefault()
    }
  });
  document.addEventListener('gesturestart', function(event) {
    event.preventDefault()
  })
}